A trial comparing the treatment with dose-escalated external beam radiotherapy found that it was much more successful at banishing cancer.

Men who underwent LDR-PB were twice as likely to be cancer-free five years later.

Scientists studied 398 men with cancer that had not spread outside the prostate gland who were judged to be at high risk of treatment failure based on standard test results.

Lead researcher Professor James Morris, from Vancouver Cancer Centre in Canada, said: “At five years follow-up, we saw a large advantage in progression-free survival in the LDR-PB group.

“Although, to date, overall survival and prostate cancer-specific survival do not appear to differ between the two groups, existing trends favour LDR-PB and an overall survival advantage is likely to emerge with longer follow-up.”

The findings were presented at the third European Society for Radiotherapy and Oncology forum in Barcelona, Spain.

Brachytherapy was highly cost-effective but required a long period of training and experience to produce consistent results, the scientists said.

Further research iwas needed to compare the treatment with temporary high-dose brachytherapy implants and other forms of radiotherapy, they said.

Temporary brachytherapy involves inserting high-dose radioactive seeds for a few minutes at a time. Although the permanent implants remain in place, their radioactivity fades over time.